Reverse 911 is a communications tool that uses a combination of database and GIS mapping technologies to deliver outbound notifications to communities and organizations. For example, reverse 911 allows emergency services to inform the public of a known hazard and/or emergency. However, cellular or voice over IP (VoIP) phone numbers are not automatically entered in the reverse 911 system database. In some locations, if a user would like to be contacted via a cell phone by the reverse 911 system, the user may register online or by filling out a physical form with the contact information associated with a cellular device.